1. Field of the Invention
The present invention generally relates to infrared illuminators and more specifically, to near infrared illuminators with a rangefinding capability and infrared viewing enhancement.
2. Description of Prior Art
Near infrared (NIR) illuminators have been used in night vision technology to enhance viewing with an infrared viewing (I.sup.2) device. Some of the types of illuminators in the prior art include those for: aiming, boresight alignment, object illumination, and cueing.
Two types of NIR illuminators involve the aiming and alignment of a weapon. A NIR illuminator referred to as an aiming light, emits from a weapon an infrared beam reflected off a target. An operator using an I.sup.2 device (such as night vision goggles) using the aiming light will have sighted and thus "zeroed" on that target. Boresight alignment uses a NIR illuminator called a boresight light which is inserted into a boresight mechanism. This allows the operator, using night vision goggles, to observe the positions of, and thus align and position the boresight and aiming light.
When using night vision equipment it is often necessary to illuminate objects of interest with a NIR source when viewed with an I.sup.2 device. In a surveillance situation the use of a NIR radiation source will illuminate a field of view. NIR retro-reflecting markers can be used to make specific location points visible in a field of view. NIR illuminators may also be used to illuminate an operator work space. Cueing involves using a NIR illuminator to alert an operator to an obstacle in ones path. A device or operator receives a reflection from an object in the path of the operator which is then used to take evasive action, which is commonly called terrain avoidance.
Each of the NIR illumination methods discussed above are deficient in that no information is obtained as to range. Range information is needed when using an aiming light because weapons are zeroed for a specific range and in terrain avoidance so that the operator can judge how much distance can be allowed to avoid what is in the path. Also, the above methods are of a fixed field of view so there is no simple way available for an operator to adjust the device to obtain more information without diverting from the object or target.
While the prior art has reported using NIR illuminators, none have established a basis for a specific method and apparatus that is dedicated to the task of resolving the particular problem at hand. What is needed in this instance is a NIR illuminator for infrared viewing enhancement rangefinding capability.